[Branch 2.7] Avoid potentially blocking calls to metadata in PersistentTopic#getMessageTTL

[Jason918]

Motivation

This PR is part of work of cherry-pick #12340 to branch 2.7

There is a concurrent issue when updating namespace TTL, causing AdminApiTest#testTopicStatsLastExpireTimestampForSubscription fails periodically.

The root cause is that in NamespacesBase#internalSetNamespaceMessageTTL:

• Step A, we write new namespace policy data to zk
• Step B, we call policiesCache().invalidate to disable the cache.

But between Step A and B, ZooKeeperDataCache will receive a data change event, and new data of policiesCache will be reloaded in ZooKeeperDataCache#reloadCache. So this reloaded data will invalidated in Step B.

And in PersistentTopic#onPoliciesUpdate (triggered by Step A) won't be able to get policy data with policiesCache().getDataIfPresent, so checkMessageExpiry is skipped and results in AdminApiTest#testTopicStatsLastExpireTimestampForSubscription failure.

Modifications

Remove policiesCache().invalidate in Step B.

Verifying this change

• Make sure that the change passes the CI checks.

Documentation

Check the box below or label this PR directly.

• doc-not-needed

Bug fix

[Jason918]

/pulsarbot run-failure-checks

[Jason918]

@codelipenghui @merlimat @mattisonchao @Technoboy- PTAL